Two separate set points can be adjusted by the user from 6 to 8 pH and 500 to 900 mV. The relays are activated when the pH exceeds or the mV falls below the relevant set point. HI 9912 accepts any pH and ORP electrode ending in a universal BNC connector. Two independent terminals provide for pH and ORP matching pin/ ground probes to extend electrode life and eliminate interference.

HANNA's proportional control allows considerable savings by minimising the use of chemicals. The settings are made through independent time cycles adjustable from 0 to 90 seconds and two proportional bands from 0 to 200 mV and 0 to 2 pH. Two pumps or electro valves can be wired directly to the controller and be powered through the terminal.

The HI 9912's alarm is activated when measurements exceed the operator-adjustable thresholds of 50 to 250 mV or 0.5 to 2.5 pH. Should the two max dosing periods of 1 to 10 minutes be exceeded an alarm is activated to signal the abnormality. The alarm is alterable in a normally-closed or a normally-open state and can be turned off during maintenance. A pools status can be ascertained from a distance through dosage and alarm LED's.

Please note: pH and ORP probes for this unit are sold seperately.